Boil, covered, the fish broth, the diced Jerusalem artichoke, and a rose bud for 10 minutes.
Afterwards, blend until smooth and then strain.
For the rose broth, boil in water and salt 7 rose petals and leave them to infuse, covered, for 10 minutes.
For the sweet and sour sauce, heat the white vinegar and dissolve the sugar and salt.
Prepare the rose petals by boiling the water and salt, removing the pot from the stove and add the white rise.
Leave it to infuse for 12 minutes, let it cool.
Soak the mustard seeds for 24 hours, cook in a pressure cooker with 8 g of salt for each liter of water used.
After cooking, let them cool off in their own cooking water, then change the water to get rid of the bitterness.
For the salt cod, create slices of around 45 g, cook them slowly in 60°C oil until the centre of the slices have reached 45°C.
A cooking thermometer will help you with this.